Tubular organs in the body, such as the gastrointestinal (GI) tract, may have abnormalities, such as, strictures, narrowings or closures. These abnormalities may affect the anatomy or topology of the organs. Such abnormalities may be formed, for example, by calcification, scar tissue, tumors or other pathologies. Crohn disease, for example, which is typically a chronic inflammatory disease of the small bowel, may cause ulcers in the inner surface of the small bowel. In severe cases, large or deep ulcers may develop causing scarring and stiffness and possibly narrowing the small bowel. These abnormalities may obstruct the flow of material through the organs.
Methods for detecting abnormalities of the body lumen are often invasive, but some are non-invasive.
Some non-invasive methods for detecting abnormalities, specifically in the GI tract, include x-ray detection. In one method, x-ray opaque (radio-opaque) material (e.g., barium or gastrographine) may be ingested by a patient and a series of x-ray images that record the x-ray material in the body are captured. The material resides for some time on the walls of the GI tract, enabling examination of the x-ray images of the GI tract. This technique has several drawbacks, such as poor detection rate and patient exposure to x-ray radiation.
Other non-invasive techniques use solid non-degradable swallowable autonomous electronically or magnetically marked capsules. Electronically marked capsules may transmit electro-magnetic signals to a receiver external to the body to track the movement of the capsule through the GI tract. Magnetically marked capsules may alter the magnetic field, which may be measured to track the movement of the capsules in the GI tract. Magnetically marked capsule may be solid non-degradable capsules, e.g., containing powdered magnetite encapsulated in silicone rubber (W. Weitschies, R. Kotitz, D. Cardin, L. Trahms, (1997), J Pharm Sci, 86:1218-1222). Autonomous capsules may also be used to measure in-vivo conditions, such as gastric pH (e.g., using the Heidelberg capsule) and in-vivo temperature (e.g., using the CoreTemp™ capsule). Autonomous capsules are typically propelled through the GI tract by natural peristalsis. Autonomous capsules may monitor regions in the intestine, especially distal parts of the small intestine (e.g., the jejunum and ileum), that cannot be reached by other methods or devices. However, in cases where large strictures are located in narrow regions of the GI tract such as the small bowel, swallowing a solid bolus such as an autonomous capsule may itself cause an obstruction of the GI tract.
A method to determine if a stricture is large enough to prevent the safe passage of an autonomous medical device through the GI tract may include monitoring the passage of a test device resembling the medical device.
U.S. Pat. No. 7,083,578 describes passing a test device through the body. In one embodiment, the test device is an electronically marked autonomous capsule that transmits signals from inside the body to an external device outside of the body. If, after a period of time has elapsed, namely the predetermined period of time in which an unobstructed capsule should normally pass through the body, the external device may test whether or not the capsule is still transmitting signals from the body. If the external device receives no signals from the capsule, it may be determined that the capsule has been excreted from the patient's body. However, if the time period for the capsule passage has elapsed and the external device still receives signals, it may be determined that the capsule is stuck within the body lumen, for example, at the narrow passage of the small bowel.
Although the methods described in U.S. Pat. No. 7,083,578 may accurately determine if an autonomous device is stuck in a patient's body, this process has some drawbacks. For example, the time period in which an unobstructed capsule should typically stay in its initial dimensions is approximately thirty to a hundred hours. A patient is instructed to be on a liquid diet from noon of the first day. In the morning that follows, the patient may ingest the capsule. A practitioner would typically wait for thirty hours from the time the capsule was ingested by the patient to determine if the capsule is retained within the patient. After thirty hours, the practitioner may use an external scanner to scan the patient's abdomen and check signals are still emanating from the capsule. This amount of time prevents the use of imaging capsules shortly after test capsules.
Accordingly, there is a need in the art for a more efficient device, system and method to determine, within a relatively short period of time, if an autonomous device of a certain size and/or shape will pass safely through the GI tract, specifically through the small bowel.